This invention relates to a device to drain leakage liquids from an aircraft auxiliary power unit (“APU”), maintaining fireproof conditions at APU compartment. It is included in the technical field of auxiliary power units for aerospace industry.
Most modern aircraft include an APU as standard operational equipment. Typically, the APU is positioned in a compartment located at the aircraft tail cone portion.
APU compartments must fulfill fireproof requirements. In case of a fire in the APU compartment, its structure must be capable of resisting damages produced by flames. Moreover, no flame can enter any part of the APU due to explosion danger.
Access to the APU compartment is provided through maintenance doors. These doors must fulfill the fireproof requirements of the APU compartment, but they must also provide the draining necessities. So the problem solved by this invention is how to guarantee fireproof conditions at the APU compartment, maintaining drainage capability of leakage fluids.
The state of the art presents some references about how to deal with leakage fluids and how to keep fireproof conditions in APU compartments as well. However, no evidences about how to solve these two problems together have been found.
Document U.S. Pat. No. 3,556,444 A discloses an apparatus for controlling the discharge of leakage fluids from the jet engines of an aircraft, wherein removed fluids are directed into the exhaust jet of the engines for combustion.
Document EP 1 062 155 B1 shows an apparatus for draining fluid from an aircraft auxiliary power unit, wherein the fluids are drained by gravity through a check valve.
Document EP 2 147 862 A2 reveals an auxiliary power unit inlet door actuation mechanism to be used at fireproof enclosures.